Yes, the plastic or glass can act as a magnifier. I wasn't trying to scare anyone into not using a tote (the tote is WAY better than glass tanks) i was just saying to make sure folks are aware it can happen. I live in las vegas right now and the sun here is insanely intense an overheat could happen here in less than 5 minutes, and if they are in any kind of container where they can't seek shade it could be deadly.